Apparatus for controlling rotary machine

ABSTRACT

In a control apparatus, a filter processor filters target torque for a rotary electric machine to suppress a vibrational frequency component of a drivetrain using a filter having a frequency transfer characteristic. A controller performs drive control of the rotary electric machine according to the filtered target torque. A parameter calculator calculates, according to a running condition of the vehicle, a parameter associated with a request value for responsivity of output torque of the rotary electric machine with respect to the target torque. A variable setter variably sets the frequency transfer characteristic of the filter to decrease a degree of attenuation of the vibrational frequency component with an increase of the request value for responsivity of the actual output torque. A limiter limits a rate of change of the degree of attenuation to suppress vibrations of the drivetrain.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from Japanese Patent Application 2014-169111 filed on Aug. 22, 2014, the disclosure of which is incorporated in its entirety herein by reference.

TECHNICAL FIELD

The present disclosure relates to apparatuses for controlling a rotary electric machine that supplies drive power to driving wheels of a vehicle via a drivetrain, i.e. a power transmission mechanism.

BACKGROUND

Such control apparatuses include a control apparatus for suppressing vibrational frequency components occurring from the drivetrain, which is for example disclosed in Japanese Patent Publication No. 5324623. In detail, the control apparatus, which is installed in a vehicle, filters target torque for a motor as an example of rotary electric machines to suppress such vibrational frequency components contained in the target torque. Then, the control apparatus controls actual output torque of the motor using the filtered target torque.

SUMMARY

The control of actual output torque of a motor based on the filtered target torque may reduce the responsivity of the control as compared with the control of actual output torque of the same motor based on unfiltered target torque. The control of actual output torque of the motor with respect to the filtered target torque may therefore cause a disadvantage, such as reduction of the driver's drivability of the vehicle, under some situations where the higher responsivity of the torque control of the motor should be desired, including a situation where the driver wants to make the vehicle maneuver quickly.

In view of the circumstances set forth above, one aspect of the present disclosure seeks to provide apparatuses for controlling a rotary electric machine, which are capable of addressing such a problem.

Specifically, an alternative aspect of the present disclosure aims to provide such apparatuses each capable of reducing a disadvantage due to filtering of target torque to suppress a vibrational frequency component included in the target torque.

According to an exemplary aspect of the present disclosure, there is provided a control apparatus for a rotary electric machine of a vehicle. The vehicle is equipped with a drivetrain for transmitting power output from the rotary electric machine to driving wheels. The control apparatus includes a filter processor that filters target torque for the rotary electric machine to suppress a vibrational frequency component of the drivetrain using a filter having a frequency transfer characteristic. The control apparatus includes a controller that performs drive control of the rotary electric machine according to the filtered target torque. The control apparatus includes a parameter calculator that calculates, according to a running condition of the vehicle, a parameter associated with a request value for responsivity of output torque of the rotary electric machine with respect to the target torque. The control apparatus includes a variable setter that variably sets the frequency transfer characteristic of the filter to decrease a degree of attenuation of the vibrational frequency component with an increase of the request value for responsivity of the actual output torque. The control apparatus includes a limiter that limits a rate of change of the degree of attenuation to suppress vibrations of the drivetrain.

The control apparatus according to the exemplary aspect calculates the parameter associated with the request value for responsivity of output torque of the rotary electric machine according to the running condition of the vehicle. That is, the parameter represents how the responsivity of the output torque is set. The control apparatus according to the exemplary aspect variably sets the frequency transfer characteristic of the filter to decrease the degree of attenuation of the vibrational frequency component with an increase of the request value for responsivity of the actual output torque.

Reducing the degree of attenuation of the vibrational frequency component with an increase of the request value for responsivity of the actual output torque reduces the delay in phase of the frequency transfer characteristic. This reduces the response delay of an output value from the filter in response to an input value to the filter. This maintains the responsivity of torque control at a higher level to enable improvement of a driver's drivability of the vehicle in a situation where the driver has an intention to make the vehicle maneuver quickly.

In contrast, increasing the degree of attenuation of the vibrational frequency component with a decrease of the request value for responsivity of the actual output torque reduces the responsivity of torque control at a relatively lower level to increase the effects of suppressing vibrations of the drivetrain of the vehicle.

This enables improvement of the driver's comfort in the vehicle.

That is, the control apparatus according to the exemplary aspect adjusts the responsivity of torque control according to the running condition of the vehicle, thus reducing a disadvantage due to filtering of the target torque for the rotary electric machine.

Additionally, the control apparatus according to the exemplary aspect limits change of the degree of attenuation to suppress vibrations of the drivetrain. This reduces vibrational frequency components included in the target torque due to change of the degree of attenuation, thus suppressing vibrations of the vehicle due to change of the degree of attenuation.

The above and/or other features, and/or advantages of various aspects of the present disclosure will be further appreciated in view of the following description in conjunction with the accompanying drawings. Various aspects of the present disclosure can include and/or exclude different features, and/or advantages where applicable. In addition, various aspects of the present disclosure can combine one or more feature of other embodiments where applicable. The descriptions of features, and/or advantages of particular embodiments should not be construed as limiting other embodiments or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects of the present disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings in which:

FIG. 1 is a block and structural diagram schematically illustrating an example of the structure of a control system installed in a vehicle according to the first embodiment of the present disclosure;

FIG. 2 is a block diagram schematically illustrating an example of the structure of a second ECU illustrated in FIG. 1;

FIG. 3A is a graph schematically illustrating how curves of filtered target MG torque change over time; the curves correspond to different values of a target attenuation coefficient;

FIG. 3B is a graph schematically illustrating how curves of output torque of a drive shaft illustrated in FIG. 1 change over time; the curves correspond to different values of the target attenuation coefficient;

FIG. 4A is a graph schematically illustrating how an attenuation parameter according to the first embodiment and that according to a related technology change over time;

FIG. 4B is a graph schematically illustrating how actual output torque of a motor-generator illustrated in FIG. 1 according to the first embodiment and that of the motor-generator according to the related technology change over time;

FIG. 4C is a graph schematically illustrating how the output torque of the drive shaft according to the first embodiment and that according to the related technology change over time according to the first embodiment;

FIG. 5 is a block diagram schematically illustrating an example of the structure of a second ECU according to the second embodiment of the present disclosure;

FIG. 6 is a block diagram schematically illustrating an example of the structure of a second ECU according to the third embodiment of the present disclosure;

FIG. 7 is a block and structural diagram schematically illustrating an example of the structure of a control system installed in a vehicle according to the fourth embodiment of the present disclosure;

FIG. 8 is a graph schematically illustrating how each of request torque, target MG torque, and actual output torque of the motor-generator according to the fourth embodiment;

FIG. 9 is a graph schematically illustrating the attenuation parameter stepwisely varies over time as a limited attenuation parameter according to a modification of the first embodiment; and

FIG. 10 is a graph schematically illustrating the attenuation parameter varies over time in the form of a first order lag function as the limited attenuation parameter according to another modification of the first embodiment.

DETAILED DESCRIPTION OF EMBODIMENT

The following describes embodiments of the present disclosure with reference to the accompanying drawings. In the embodiments, like parts between the embodiments, to which like reference characters are assigned, are omitted or simplified to avoid redundant description.

First Embodiment

The following describes a first embodiment of the present disclosure, to which an apparatus for controlling a rotary electric machine serving as a main engine of a vehicle VEH is applied, with reference to FIGS. 1 to 4.

Referring to FIG. 1, the vehicle VEH includes a motor-generator (MV) 10, an inverter 12, a battery 14, a drive shaft 16, and driving wheels 18. The vehicle VEH also includes a first electronic control unit (ECU) 30 and a second ECU 32.

The motor-generator 10 serves as both a motor and a generator; the motor serves as a driving source for running the vehicle VEH. The first embodiment uses a multiphase rotary machine, particularly, a three-phase rotary machine including three-phase windings (U, V, W-phase windings) as the motor-generator 10. Specifically, the first embodiment is capable of using, for example, a three-phase synchronous motor as the motor-generator 10.

A three-phase voltage-controlled inverter is used as the inverter 12 when a three-phase rotary machine is used as the motor-generator 10. The inverter 12 converts a direct-current (DC) voltage output from the battery 14 into an alternating-current (AC) voltage, and applies the AC voltage to the motor-generator 10. This voltage application causes the motor-generator 10 to serve as a motor. In contrast, the motor-generator 10 serves as a generator based on driving power received from the drive shaft 16.

The motor-generator 10 has a rotor 10 r and an output shaft 10 a, which will be referred to as a motor output shaft 10 a, coupled to the rotor 10 r.

To the output shaft 10 a, the driving wheels 18 are coupled via the drive shaft 16. The first embodiment defines, for example, a drivetrain, which is also called power transmission mechanism or powertrain, including the motor output shaft 10 a and the drive shaft 16.

The vehicle VEH further includes a rotational speed sensor 20. The rotational speed sensor 20 measures a rotational speed of the motor output shaft 10 a, i.e. the rotor 10 r, which will be referred to as a motor rotational speed Nm. The measurement value of the rotational speed sensor 20 is input to the second ECU 32. Note that the first embodiment can provide a sensor in the vehicle VEH; the sensor is capable of measuring an electrical rotational angle or an electrical rotational angular velocity of the rotor 10 r of the motor-generator 10. In this case, the second ECU 32 can calculate the motor rotational speed Nm according to the measured electrical rotational angle or electrical angular speed of the rotor 10 r.

The vehicle VEH additionally includes current sensors 34. The current sensors 34 are operative to measure currents flowing through at least two windings, for example, V- and W-phase windings, in the three-phase windings of the motor-generator 10 as V- and W-phase currents. Then, the current sensors 34 send the measured V- and W-phase currents to the second ECU 32.

Each of the first and second ECUs 30 and 32 is designed as, for example, a microcomputer circuit including essentially, for example, a CPU, a memory unit including a ROM and a RAM, and input/output units. Each of the first and second ECUs 30 and 32, i.e. a corresponding CPU, runs various programs stored in, for example, the ROM. The first and second ECUs 30 and 32 are configured to communicate information with each other.

The first ECU 30 is superior in hierarchy to the second ECU 32. That is, the first ECU 30 is, for example, an upstream control unit with respect to the second ECU 32 in the flow of addressing vehicle's user requests. For example, the first ECU 30 supervises overall control of the vehicle VEH. Specifically, the first ECU 30 determines target torque, referred to as target MG torque, Tm* for the motor-generator 10 according to measurement signals including, for example,

(1) A user's operated (depressed) quantity, i.e. stroke, Acc of a user-operable accelerator pedal (not shown) of the vehicle VEH, which will be referred to as an accelerator operated stroke Acc

(2) A user's operated (depressed) quantity, i.e. stroke, Brk of a user-operable brake pedal (not shown) of the vehicle VEH, which will be referred to as a brake operated stroke Brk

(3) A running speed V of the vehicle VEH.

In the first embodiment, if the target MG torque Tm* is positive, the control mode of the inverter 12 by the second ECU 32 is set to a power running mode for causing the motor-generator 10 to serve as a motor. In contrast, if the target MG torque Tm* is negative, the control mode of the inverter 12 by the second ECU 32 is set to a regenerative mode for causing the motor-generator 10 to serve as a generator. In particular, the first ECU 30 of the first embodiment increases a value of the target MG torque Tm* with an increase of the accelerator operated stroke Acc in the power running mode.

The brake operated stroke Brk represents a value of driver's requested brake torque for slowing down the vehicle VEH. In other words, the second ECU 32 calculates a value of the driver's requested brake torque for slowing down the vehicle VEH according to the brake operated stroke Brk.

In addition, the first ECU 30 outputs the target MG torque Tm* to the second ECU 32.

For example, in the first embodiment, an accelerator-pedal sensor 36 is provided to measure the accelerator operated stroke Acc, and send the accelerator operated stroke Acc to the first ECU 30. For example, in the first embodiment, a brake-pedal sensor 38 is provided to measure the brake operated stroke Brk, and send the brake operated stroke Brk to the first ECU 30. For example, in the first embodiment, a vehicle speed sensor 40 is provided to measure the running speed V of the vehicle VEH, and send the running speed V to the first ECU 30.

The second ECU 32 serves as a control unit for controlling the motor-generator 10. The second ECU 32 receives the target MG torque Tm*, the accelerator operated stroke Acc, the brake operated stroke Brk, and the running speed V input from the first ECU 30, and receives the measurement values input from the rotational speed sensor 20.

Then, the second ECU 32 operates, based on the received values, in the power running mode or the regenerative mode to control on-off operations of for example, bridge-connected switching elements of the inverter 12. This converts the DC voltage output from the battery 14 into controlled three-phase AC voltages, thus applying the controlled three-phase AC voltages to the three-phase windings of the motor-generator 10. This controls torque of the motor-generator 10 for rotating the rotor 10 r to follow the target MG torque Tm*.

In particular, in the regenerative mode, the second ECU 32 performs a regenerative control task of the motor-generator 10. The regenerative control task is configured to

(1) Calculate the driver's requested brake torque for slowing down the vehicle VEH according to the brake operated stroke Brk

(2) Satisfy the calculated driver's requested brake torque based on a negative value of output torque of the motor-generator 10 controlled to follow a negative value of the target MG torque Tm* and brake torque generated by a brake system 50 for applying brake force to each wheel of the vehicle VEH to slow down the vehicle VEH.

The negative value of the output torque of the motor-generator 10, which will also be referred to as regenerative torque of the motor-generator 10, serves the motor-generator 10 as a generator to generate AC electrical energy, i.e. regenerative power, based on kinetic energy of the driving wheels 18 of the vehicle VEH. The generated AC electrical energy is converted into DC electrical energy by the inverter 12, and the DC electrical energy is charged into the battery 14.

The second ECU 32 of the first embodiment shifts its operating mode to the regenerative mode from the power running mode to perform the regenerative control task of the motor-generator 10 on the conditions that

(1) The running speed V is equal to or higher than a predetermined threshold speed zero predetermined to be higher than zero

(2) The driver is not operating the accelerator pedal

(3) The driver is operating the brake pedal.

The second ECU 32 is capable of determining whether the driver is not operating the accelerator pedal according to the accelerator operated stroke Acc, and determining whether the driver is operating the brake pedal according to the brake operated stroke Brk.

The second ECU 32 operates in the regenerative mode under one of the following conditions:

(1) The vehicle VEH is slowing down while the driver is operating the brake pedal

(2) The vehicle VEH is running downhill while the running speed V is maintained at a predetermined speed with the brake pedal being operated by the driver.

In the regenerative mode, the second ECU 32 can calculate the vehicle speed V according to the motor rotational speed Nm.

Next, the following describes an example of the specific structure of the second ECU 32 for performing torque control of the motor-generator 10 based on the target MG torque Tm* with reference to the block diagram of FIG. 2.

As illustrated in FIG. 2, the second ECU 32 includes a calculator 32 a, a limiter 32 b, a target attenuation-coefficient setter 32 c, a filter processor 32 d, and a drive controller 32 d 1. These elements 32 a to 32 d 1 can be implemented in the second ECU 32 as hardware elements, software elements, and/or hardware-software hybrid elements.

These elements 32 a to 32 d 1 are configured to suppress resonance of the drivetrain when, for example, the target MG torque Tm* rapidly changes, thus suppressing vibrations of the vehicle VEH. Resonance of the drivetrain occurs due to, for example, resonant frequency components of the drivetrain contained in the target MG torque Tm* when, for example, the target MG torque Tm* suddenly changes. For example, the resonance of the drivetrain can be expressed as a known torsional vibration model, more specifically as a known first harmonic drivetrain torsional vibration model.

Specifically, the torsional vibration model of the drivetrain is comprised of a model including the moment of inertia of the motor-generator 10 and the equivalent mass moment of inertia of the vehicle VEH linked together via a torsional spring. The resonant frequency frz of the drivetrain is variably set within, for example, the range from 2 to 10 Hz inclusive.

The calculator 32 a calculates, according to running conditions of the vehicle VEH including the accelerator operated stroke Acc, the brake operated stroke Brk, and/or the running speed V, an attenuation parameter Atp. The attenuation parameter Atp serves as a parameter associated with a request value for the responsivity of the actual output torque Tm of the motor-generator 10 with respect to the target MG torque Tm*; the responsivity will be referred to as a torque responsivity of the motor-generator 10. The attenuation parameter Atp also serves as a parameter for determining how vibrational frequency components are attenuated.

Specifically, the calculator 32 a calculates the attenuation parameter Atp such that the attenuation parameter Atp decreases with an increase of the request value for the torque responsivity of the motor-generator 10.

In particular, the calculator 32 a reduces the attenuation parameter Atp with an increase of change of the accelerator operated stroke Acc per unit time. In other words, the calculator 32 a adjusts the attenuation parameter Atp such that a value of the attenuation parameter Atp for a first case is smaller than a value of the attenuation parameter Atp for a second case. The first case represents a case where an increase of the accelerator operated stroke Acc per unit time is greater than a predetermined threshold change, i.e. a predetermined threshold increase, of the accelerator operated stroke Acc per unit time. The second case represents a case where an increase of the accelerator operated stroke Acc per unit time is equal to or smaller than the predetermined threshold increase, of the accelerator operated stroke Acc per unit time.

Additionally, the calculator 32 a reduces a value of the attenuation parameter Atp during execution of the regenerative control task to be smaller than a value of the attenuation parameter Atp while the regenerative control task is not being executed. The calculator 32 a can determine whether the second ECU 32 is carrying out the regenerative control task according to the accelerator operated stroke Acc, the brake operated stroke Brk, and the running speed V.

Specifically, the calculator 32 a is capable of determining, according to the accelerator operated stroke Acc, the brake operated stroke Brk, and/or the running speed V,

(1) Whether the driver has an intention to make the vehicle VEH accelerate

(2) Whether the regenerative control task is being performed.

The limiter 32 b applies a limiting task to the attenuation parameter Atp, and outputs a limited attenuation parameter Attr to which the limiting task has been applied. The limiting task will be described later.

The target attenuation-coefficient setter 32 c variably sets a target attenuation-coefficient ξ_(tag), which represents a target value of the degree of attenuation of the vibrational frequency components, according to the limited attenuation parameter Attr. For example, the target attenuation-coefficient setter 32 c of the first embodiment can have relational information RI, such as a two-dimensional map illustrated in FIG. 2 or an equation, in which values of the target attenuation-coefficient ξ_(tag) correlating with corresponding values of the limited attenuation parameter Attr are included. In FIG. 2, the relational information RI represents that the target attenuation-coefficient ξ_(tag) is a linear function of the limited attenuation parameter Attr with a positive gradient.

In this case, the target attenuation-coefficient setter 32 c refers to the relational information RI using a value of the limited attenuation parameter Attr as input data to read a value of the target attenuation-coefficient ξ_(tag) corresponding to the input data value of the limited attenuation parameter Attr. Then, the target attenuation-coefficient setter 32 c outputs the value of the target attenuation-coefficient ξ_(tag) to the filter processor 32 d.

For example, the target attenuation-coefficient setter 32 c increases the target attenuation-coefficient ξ_(tag) with an increase of the limited attenuation parameter Attr. In particular, the target attenuation-coefficient setter 32 c of the first embodiment sets the target attenuation-coefficient ξ_(tag) to a prescribed attenuation-coefficient ξ_(p) when the limited attenuation parameter Attr becomes its minimum value Attmin, and to 1 when the limited attenuation parameter Attr becomes its maximum value Attmax. Note that the attenuation-coefficient ξ₁ is previously set to be a value more than zero and less than 1.

The filter processor 32 d filters the target MG torque Tm* based on a filter having predetermined filter transfer characteristics I(s) while adjusting the filter transfer characteristics I(s) according to the target attenuation-coefficient ξ_(tag) output from the target attenuation-coefficient setter 32 c; s represents Laplace operator.

Let us describe the filter transfer characteristics I(s) according to the first embodiment.

First, let us develop frequency transfer characteristics of a vehicle plant model having torque output from the motor-generator 10 to the motor output shaft 10 a as its input, and output torque Tds of the drive shaft 16 as its output. The frequency transfer characteristics will also be referred to as modeled transfer characteristics Gpm(s). The first embodiment expresses the equations of motion of a vehicle by the following equations [eq1] to [eq6]:

$\begin{matrix} {{{J_{m} \cdot \frac{}{t}}\omega_{m}} = {T_{m} - \frac{T_{ds}}{N_{al}}}} & \left\lbrack {{eq}\mspace{14mu} 1} \right\rbrack \\ {{2\; {J_{w} \cdot \frac{}{t}}\omega_{w}} = {T_{ds} - {r \cdot F}}} & \left\lbrack {{eq}\mspace{14mu} 2} \right\rbrack \\ {{{M_{c} \cdot \frac{}{t}}V_{c}} = F} & \left\lbrack {{eq}\mspace{14mu} 3} \right\rbrack \\ {T_{ds} = {K_{d} \cdot \theta}} & \left\lbrack {{eq}\mspace{14mu} 4} \right\rbrack \\ {F = {K_{t}\left( {{r \cdot \omega_{m}} - V_{c}} \right)}} & \left\lbrack {{eq}\mspace{14mu} 5} \right\rbrack \\ {\theta = {\int{\left( {\frac{\omega_{m}}{N_{al}} - \omega_{w}} \right){t}}}} & \left\lbrack {{eq}\mspace{14mu} 6} \right\rbrack \end{matrix}$

Where:

J_(m) represents the inertia of the rotor 10 r of the motor-generator 10

J_(w) represents the inertia of the driving wheels 18

ω_(m) represents the angular frequency of the rotor 10 r of the motor-generator 10

ω_(w) represents the angular frequency of the driving wheels 18

T_(m) represents output torque of the motor-generator 10

T_(ds) represents actual output torque of the driving wheels 18, i.e. the drive shaft 16

N_(al) represents an overall gear ratio of the vehicle VEH

K_(d) represents torsional rigidity of the drivetrain, i.e. the drive shaft

r represents a dynamic loaded radius of each wheel of the vehicle VEH

F represents drive power of the vehicle VEH

M_(c) represents the mass of the vehicle VEH

V_(c) represents the running speed of the vehicle VEH

θ represents a twisting angle of the drive shaft 16.

Performing Laplace transform of these equations [eq1] to [eq6] results in expression of the modeled transfer characteristics Gpm(s) by the following equation [eq7]:

$\begin{matrix} {{{Gpm}(s)} = {\frac{T_{ds}}{T_{m}} = {\frac{K_{d}\left( {{p_{1} \cdot s} + p_{0}} \right)}{{a_{3} \cdot s^{3}} + {a_{2} \cdot s^{2}} + {a_{1} \cdot s} + a_{0}} = \frac{K_{d}\left( {{p_{1} \cdot s} + p_{0}} \right)}{{a_{3}\left( {s + \alpha} \right)}\left( {s^{2} + {2\; {\xi_{p} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}} \right)}}}} & \left\lbrack {{eq}\mspace{14mu} 7} \right\rbrack \end{matrix}$

Where

$p_{1} = {\cdot \frac{2\; {J_{m} \cdot M_{c}}}{N_{al}}}$ $p_{0} = \frac{K_{t}\left( {{2\; J_{w}} + {r^{2} \cdot M_{c}}} \right)}{N_{al}}$ a₃ = 2 J_(m) ⋅ J_(w) ⋅ M_(c) a₂ = K_(t) ⋅ J_(m)(2 J_(w) + r² ⋅ M_(c)) $a_{1} = {K_{d} \cdot {M_{c}\left( {J_{m} + \frac{2\; J_{W}}{N_{al}^{2}}} \right)}}$ $a_{0} = {K_{d} \cdot {K_{t}\left( {J_{m} + \frac{2\; J_{w}}{N_{al}^{2}} + \frac{r^{2} \cdot M_{c}}{N_{al}^{2}}} \right)}}$

In the equation [eq7], reference character s represents the Laplace operator, and reference character ξ_(p) of the second-order lag element represents the prescribed attenuation coefficient, which is an attenuation coefficient for the drivetrain. In the equation [eq7], reference character cop of the second-order lag element represents a resonant angular frequency, i.e. a natural angular frequency, of the drivetrain. The first embodiment respectively sets the resonant angular frequency φp and the prescribed attenuation coefficient ξ_(p) to fixed values. The reason why the modeled transfer characteristics Gpm(s) are expressed by the equation [eq7] is that actual frequency transfer characteristics Gpr(s) of the drivetrain, to which reference character 40 is assigned, is approximated by the equation [eq7].

Next, let us express target frequency transfer characteristics of a target vehicle plant model, which has torque output from the motor-generator 10 to the motor output shaft 10 a as an input, and output torque Tds of the drive shaft 16 as an output, by the following equation [eq8]:

$\begin{matrix} {{{Gr}(s)} = \frac{K_{d}\left( {{p_{1} \cdot s} + p_{0}} \right)}{{a_{3}\left( {s + \alpha} \right)}\left( {s^{2} + {2\; {\xi_{tag} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}} \right)}} & \left\lbrack {{eq}\mspace{14mu} 8} \right\rbrack \end{matrix}$

Where Gr(s) represents the target frequency transfer characteristics of the target vehicle plant model.

Replacing the prescribed attenuation coefficient ξ_(p) described in the equation [eq7] with the target attenuation coefficient ξ_(tag) obtains the equation [eq8].

From the equations [eq7] and [eq8], the following equation [eq9], which expresses the filter transfer characteristics I(s), is derived as follows:

$\begin{matrix} {{I(s)} = {\frac{{Gr}(s)}{{Gpm}(s)} = \frac{s^{2} + {2\; {\xi_{p} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}}{s^{2} + {2\; {\xi_{tag} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}}}} & \left\lbrack {{eq}\mspace{14mu} 9} \right\rbrack \end{matrix}$

The dimension of the target frequency transfer characteristics, referred to as target transfer characteristics, Gr(s) and that of the modeled transfer characteristic Gpm(s) are identical to each other, resulting in the filter transfer characteristics I(s) being non-dimensional characteristics. The inverse of the modeled transfer characteristic Gpm(s) in the filter transfer characteristics I(s) serves as an inverse filter for suppressing resonance of the drivetrain.

Specifically, the filter processor 32 d is configured to filter the target MG torque Tm* based on the filter transfer characteristics I(s) expressed in the equation [eq9].

This configuration sets the target attenuation coefficient ξ_(tag) to the prescribed attenuation coefficient ξ_(p) when the limited attenuation parameter Attr becomes its minimum value Attmin. This setting causes the filter transfer characteristics I(s) to be 1, resulting in the target MG torque Tm*, which is input to the filter processor 32 d, being output from the filter processor 32 d as it is.

In contrast, the configuration sets the target attenuation coefficient ξ_(tag) to 1 when the limited attenuation parameter Attr becomes its maximum value Attmax, resulting in the target MG torque Tm*, which is input to the filter processor 32 d, being output from the filter processor 32 d while being attenuated.

FIG. 2 schematically illustrates the target MG torque Tm* output from the filter processor 32 d as filtered target MG torque, i.e. filtered target MG torque, Tam*.

FIG. 3A schematically illustrates how curves of the filtered target MG torque Tam* change over time; the curves are obtained when corresponding values of the target attenuation coefficient ξ_(tag) are set to different values within the range from 1 to the prescribed attenuation coefficient ξ_(p). FIG. 3B also schematically illustrates how curves of the output torque Tds of the drive shaft 16 change over time; the curves are obtained when corresponding values of the target attenuation coefficient ξ_(tag) are set to different values within the range from 1 to the prescribed attenuation coefficient ξ_(p).

For example, each of FIGS. 3A and 3B shows the curve, which is obtained when the corresponding target attenuation coefficient ξ_(tag) is set to the prescribed attenuation coefficient ξ_(p), drawn by a solid line. Similarly, each of FIGS. 3A and 3B shows the curve, which is obtained when the target attenuation coefficient ξ_(tag) is set to 1, drawn by a solid line.

In addition, each of FIGS. 3A and 3B shows the curves, which are obtained when corresponding three different values are assigned to the target attenuation coefficient ξ_(tag), drawn by respective dashed, dot-and-dash, and two-dot chain lines. The dashed, dot-and-dash, and two-dot chain curves have a characteristic that the corresponding values of the target attenuation coefficient ξ_(tag) increase in the order from the dashed curve, the dot-and-dash curve, to the two-dot chain curve.

FIGS. 3A and 3B show that the target MG torque Tm* steeply rises in a step function at time t1, and after the time t1, show that, the smaller the value of the target attenuation coefficient ξ_(tag) is, the more the responsivity of torque control is improved.

In particular, the filter processor 32 d can convert the filter transfer characteristics I(s) represented in a complex domain, i.e. S domain, into, for example, discretized filter transfer characteristics I(z) in a discretized complex domain, i.e. Z domain. Then, the filter processor 32 d can perform filtering of the target MG torque Tm* using the discretized filter transfer characteristics I(z).

The drive controller 32 d 1 performs on-off control of the bridge-connected switching elements of the inverter 12 according to the filtered target MG torque Tm* to convert the DC voltage output from the battery 14 into a controlled AC voltage, thus applying the controlled AC voltage to the three-phase windings of the motor-generator 10. This causes output torque of the motor-generator 10 to follow the filtered target MG torque Tam*. The drive controller 32 d 1 can perform known current vector control as an example of the on-off control of the switching elements of the inverter 12.

For example, the current vector control calculates, from the measured V- and W-phase currents, the remaining phase, i.e. the U-phase, current, and converts the three-phase currents (U-, V-, and W-phase currents) into a current value in a first axis and a current value in a second axis; the first axis and second axis define a rotating Cartesian coordinate system in the rotor 10 r. The rotating Cartesian coordinate system rotates as the rotor 10 r rotates. The current vector control obtains a first deviation between the first-axis measured current value and a first-axis command current, and a second deviation between the second-axis measured current value and a second-axis command current. Then, the current vector control obtains three-phase AC command voltages that should zero the first and second deviations. The current vector control controls on-off operations of the switching elements of the inverter 12 according to the obtained three-phase command voltages, thus causing output torque of the motor-generator 10 to follow the filtered target MG torque Tam*.

As described above, the second ECU 32, which serves as a component of a control apparatus for the motor-generator 10, calculates, according to the accelerator operated stroke Acc, the brake operated stroke Brk, and the running speed V, an attenuation parameter Atp. The attenuation parameter Atp serves as a parameter associated with a request value for the torque responsivity of the motor-generator 10. The attenuation parameter Atp also serves as a parameter for detel mining how vibrational frequency components are attenuated.

In particular, the second ECU 32 determines whether the driver has an intention to make the vehicle VEH maneuver quickly according to, for example, an increase of change of the accelerator operated stroke Acc per unit time. Then, the second ECU 32 reduces a value of the attenuation parameter Atp for a case where the driver has an intention to make the vehicle VEH maneuver quickly to be smaller than a value of the attenuation parameter Atp for a case where the driver has no intention to make the vehicle VEH maneuver quickly.

Additionally, the second ECU 32 determines whether the regenerative control task is being performed according to, for example, the accelerator operated stroke Acc, the brake operated stroke Brk, and/or the running speed V. Then, the second ECU 32 reduces a value of the attenuation parameter Atp for a case where the regenerative control task is being performed to be smaller than a value of the attenuation parameter Atp for a case where no regenerative control task is being performed.

The reduction in the value of the attenuation parameter Atp reduces the target attenuation coefficient ξ_(tag), thus improving the responsivity of the torque control (see FIGS. 3A and 3B).

Specifically, this configuration of the second ECU 32 reduces the delay in phase of the filter transfer characteristics I(s) of the filter, thus reducing the response delay of an output value from the filter in response to an input value to the filter; This

This configuration of the second ECU 32 therefore enables both improvement of the driver's drivability of the vehicle VEH and adjustment of regenerative torque of the motor-generator 10 to immediately follow the target MG torque Tm* in the regenerative mode while suppressing vibrations of the drivetrain of the vehicle VEH.

On the other hand, the second ECU 32 increases a value of the attenuation parameter Atp for a case where the driver has an intention to run the vehicle VEH with a higher degree of comfort to be larger than a value of the attenuation parameter Atp for a case where the driver has an intention to make the vehicle VEH maneuver quickly.

The increase in the value of the attenuation parameter Atp increases the target attenuation coefficient ξ_(tag), thus increasing the degree of attenuation of the target MG torque Tm* (FIGS. 3A and 3B).

Specifically, this configuration of the second ECU 32 enables improvement of the driver's comfortability of the vehicle VEH while improving the effects of suppressing vibrations of the drivetrain of the vehicle VEH.

Rapid change of the attenuation parameter Atp while the filtered target MG torque Tam* is changing may cause resonant frequency components of the drivetrain to be contained in the filtered target MG torque Tam*. The resonant frequency components might cause the vehicle VEH to vibrate.

In order to address such vibrations of the vehicle VEH due to steep change of the attenuation parameter Atp, the second ECU 32 is comprised of the limiter 32 b.

The limiter 32 b applies the limiting task to the attenuation parameter Atp to limit the rate of change of the attenuation parameter Atp. In other words, the limiter 32 b gradually changes the attenuation parameter Atp to reduce the rate of change of the attenuation parameter Atp. In particular, the limiter 32 b gradually changes the attenuation parameter Atp in the form of a linear function while having the inclination, i.e. the gradient, of the linear function gentler than the inclination, i.e. the gradient, of change of the attenuation parameter Atp.

FIGS. 4A to 4C illustrate results of the torque control including the limiting task as compared with results of the torque control without including the limiting task.

In detail, a solid line of FIG. 4A schematically illustrates how each of the attenuation parameter Atp and the limited attenuation parameter Attr changes over time according to the first embodiment. A dashed line of FIG. 4A schematically illustrates how the attenuation parameter Atp changes over time according to a related technology. The related technology is configured such that the attenuation parameter Atp is directly input to the target attenuation-coefficient setter 32 c in place of the limited attenuation parameter Attr, thus setting the target attenuation coefficient ξ_(tag) using the attenuation parameter Atp as it is.

A solid line of FIG. 4B schematically illustrates how the actual output torque Tm of the motor-generator 10 changes over time according to the first embodiment, and a dashed line of FIG. 4B schematically illustrates how the actual output torque Tm of the motor-generator 10 changes over time according to the related technology. A dot-and-dash line of FIG. 4B illustrates the target MG torque Tm* of the motor-generator 10 according to each of the first embodiment and the related technology.

A solid line of FIG. 4C schematically illustrates how the output torque Tds of the drive shaft 16 changes over time according to the first embodiment. A dashed line of FIG. 4C schematically illustrates how the output torque Tds of the drive shaft 16 changes over time according to the related technology.

FIGS. 4A to 4C demonstrate that, in the related technology, after a steep change of the target MG torque Tm* at time t10, the attenuation parameter Atp rapidly falls at time t2.

In contrast, FIGS. 4A to 4C demonstrate that the limiter 32 b limits the rate of change of the attenuation parameter Atp, in other words, gradually changes the attenuation parameter Atp to reduce the rate of change of the attenuation parameter Atp.

Thus, the second ECU 32 of the first embodiment efficiently suppresses vibrations of the vehicle VEH due to steep change of the attenuation parameter Atp.

Second Embodiment

The following describes a second embodiment of the present disclosure with reference to FIG. 5 while focusing on the different points between the second embodiment and the first embodiment.

Referring to FIG. 5, a second ECU 32A of the second embodiment includes a target attenuation-coefficient setter 32 e and a filter processor 32 f, which differ from the target attenuation-coefficient setter 32 c and filter processor 32 d, in addition to the components 32 a, 32 b, and 32 e.

For example, the target attenuation-coefficient setter 32 e of the second embodiment can have relational information RIA, such as a two-dimensional map illustrated in FIG. 5 or an equation, in which values of the target attenuation-coefficient ξ_(tag) correlating with corresponding values of the limited attenuation parameter Attr are included. In FIG. 5, the relational information RIA represents that the target attenuation-coefficient ξ_(tag) is a linear function of the limited attenuation parameter Attr with a negative gradient.

Specifically, the target attenuation-coefficient setter 32 e reduces the target attenuation-coefficient ξ_(tag) with an increase of the limited attenuation parameter Attr. In particular, the target attenuation-coefficient setter 32 e sets the target attenuation-coefficient ξ_(tag) to 1 when the limited attenuation parameter Attr becomes its minimum value Attmin, and to the prescribed attenuation-coefficient ξ_(p) when the limited attenuation parameter Attr becomes its maximum value Attmax.

The filter processor 32 f filters the target MG torque Tm* output from the target attenuation-coefficient setter 32 c based on predetermined filter transfer characteristics I(s) while adjusting the filter transfer characteristics I(s) according to the target attenuation-coefficient ξ_(tag) output from the target attenuation-coefficient setter 32 e. The second embodiment expresses modeled transfer characteristics Gpm(s) by the following equation [eq10]:

$\begin{matrix} {{{Gpm}(s)} = \frac{K_{d}\left( {{p_{1} \cdot s} + p_{0}} \right)}{{a_{3}\left( {s + \alpha} \right)}\left( {s^{2} + {2\; {\xi_{tag} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}} \right)}} & \left\lbrack {{eq}\mspace{14mu} 10} \right\rbrack \end{matrix}$

Replacing the prescribed attenuation coefficient ξ_(p) in the equation [eq7] with the target attenuation-coefficient ξ_(tag) establishes the equation [eq10].

The second embodiment also expresses target transfer characteristics Gr(s) by the following equation [eq11]:

$\begin{matrix} {{{Gr}(s)} = \frac{K_{d}\left( {{p_{1} \cdot s} + p_{0}} \right)}{{a_{3}\left( {s + \alpha} \right)}\left( {s^{2} + {2\; {\omega_{p} \cdot s}} + \omega_{p}^{2}} \right)}} & \left\lbrack {{eq}\mspace{14mu} 11} \right\rbrack \end{matrix}$

Replacing the target attenuation-coefficient ξ_(tag) in the equation [eq8] with 1 establishes the equation [eq11].

From the equations [eq10] and [eq11], the following equation [eq12], which expresses the filter transfer characteristics I(s) is derived as follows:

$\begin{matrix} {{I(s)} = {\frac{{Gpr}(s)}{{Gpm}(s)} = \frac{s^{2} + {2\; {\xi_{tag} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}}{s^{2} + {2\; {\omega_{p} \cdot s}} + \omega_{p}^{2}}}} & \left\lbrack {{eq}\mspace{14mu} 12} \right\rbrack \end{matrix}$

This configuration of the second ECU 32A of the second embodiment sets the target attenuation-coefficient ξ_(tag) to 1 when the limited attenuation parameter Attr becomes its minimum value Attmin, resulting in the filter transfer characteristics I(s) being 1. On the other hand, this configuration of the second ECU 32A sets the target attenuation-coefficient ξ_(tag) to the prescribed attenuation coefficient when the limited attenuation parameter Attr becomes its maximum value Attmax.

The limiter 32 b of the second ECU 32A of the second embodiment efficiently suppresses vibrations of the vehicle VEH due to steep change of the attenuation parameter Atp. This therefore achieves substantially the same effects as those achieved by the first embodiment.

Third Embodiment

The following describes a third embodiment of the present disclosure with reference to FIG. 6 while focusing on the different points between the third embodiment and the first embodiment.

A second ECU 32B of the third embodiment includes a limiter 32 g provided between the target attenuation-coefficient setter 32 c and the filter processor 32 d, and the limiter 32 b is eliminated. The second embodiment represents an attenuation parameter output from the calculator 32 a as the attenuation parameter Attr.

Like the first embodiment, the target attenuation-coefficient setter 32 c variably sets the target attenuation-coefficient ξ_(tag) according to the attenuation parameter Attr output from the calculator 32 a.

The target attenuation-coefficient ξ_(tag) output from the target attenuation-coefficient setter 32 c is input to the limiter 32 g.

The limiter 32 g applies a limiting task to the target attenuation-coefficient ξ_(tag) to limit the rate of change of the target attenuation-coefficient ξ_(tag). In other words, the limiter 32 g gradually changes the target attenuation-coefficient ξ_(tag) to reduce the rate of change of the target attenuation-coefficient ξ_(tag). In particular, the limiter 32 g gradually changes the target attenuation-coefficient ξ_(tag) in the form of a linear function while having an inclination of the linear function gentler than the inclination of change of the target attenuation-coefficient ξ_(tag).

A target attenuation-coefficient, to which the limiting task has been applied, will be referred to as a target attenuation-coefficient ξf hereinafter. The target attenuation-coefficient 4 f is input to the filter processor 32 d.

The filter processor 32 d filters the target MG torque Tm* output from the target attenuation-coefficient setter 32 c based on the filter transfer characteristics I(s) while adjusting the filter transfer characteristics I(s) according to the target attenuation-coefficient ξ_(f) output from the target attenuation-coefficient setter 32 c; the filter transfer characteristics I(s) is expressed by the following equation [eq13]:

$\begin{matrix} {{I(s)} = \frac{s^{2} + {2\; {\xi_{p} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}}{s^{2} + {2\; {\xi_{f} \cdot \omega_{p} \cdot s}} + \omega_{p}^{2}}} & \left\lbrack {{eq}\mspace{14mu} 13} \right\rbrack \end{matrix}$

The limiter 32 g of the third ECU 32B of the third embodiment efficiently suppresses vibrations of the vehicle VEH due to steep change of the target attenuation-coefficient ξ_(tag). This therefore achieves substantially the same effects as those achieved by the first embodiment.

Fourth Embodiment

The following describes a fourth embodiment of the present disclosure, to which an apparatus for controlling a rotary electric machine installed in a vehicle VEH1 is applied, with reference to FIGS. 7 and 8 while focusing on the different points between the fourth embodiment and the first embodiment.

Referring to FIG. 7, the vehicle VEH1 further includes a known internal combustion engine, referred to as an engine, 22 as a main engine of the vehicle VEH1 in addition to the motor-generator 10. The vehicle VEH1 also includes a power splitter 24 and a third ECU 34.

The engine 22 has a crankshaft 22 a coupled to the power splitter 24. To the power splitter 24, the motor output shaft 10 a is also coupled.

The power splitter 24 is also coupled to the drive shaft 16. For example, the power splitter 24 is configured to transfer power supplied from at least one of the engine 22 and the motor-generator 10 to the drive shaft 16, and split power supplied from the engine 22 to transfer the first split power to the drive shaft 16 and the second split power to the motor-generator 10. For example, the power splitter 24 is also configured to freely integrate power supplied from the motor-generator 10 and power supplied from the engine 22, and transfer the integrated power to the drive shaft 16. The drivetrain of the fourth embodiment includes, for example, the motor output shaft 10 a, the crankshaft 22 a, the power splitter 24, and the drive shaft 16.

The third ECU 34 is designed as, for example, a microcomputer circuit including essentially, for example, a CPU, a memory unit including a ROM and a RAM, and input/output units. The third ECU 34, i.e. a corresponding CPU, runs various programs stored in, for example, the ROM. The first ECU 30, a second ECU 32C, and the third ECU 34 are configured to communicate information with each other.

The first ECU 30 is superior in hierarchy to each of the second and third ECUs 32 and 34. That is, the first ECU 30 is, for example, an upstream control unit with respect to the second and third ECUs 32 and 34 in the flow of addressing vehicle's user requests. The first ECU 30 calculates request torque Tall of the vehicle VEH1 according to, for example, the accelerator operated stroke Acc. Then, the first ECU 30 splits the request torque Tall into target MG torque Tm* and target torque of the engine 22, which will be referred to as target engine torque Te*. Then, the first ECU 30 outputs the target MG torque Tm* allocated for the motor-generator 10 to the second ECU 32, and the target engine torque Te* allocated for the engine 22 to the third ECU 34. Note that the fourth embodiment for example assumes that the target engine torque Te* is set to be equal to or more than zero.

The third ECU 34 serves as a control unit for controlling the engine 22. The third ECU 34 receives at least the target engine torque Te* input from the first ECU 30. The third ECU 34 controls, based on the received target engine torque Te*, the proper quantity of fuel to be sprayed from an injector provided for each cylinder of the engine 22 into the combustion chamber of the corresponding cylinder, and proper ignition timing for an igniter provided for each cylinder of the engine 22. This control of the engine 22 controls actual torque generated from the engine 22 to follow the target engine torque Te*.

The calculator 32 a of the second ECU 32C adjusts the attenuation parameter Atp such that a value of the attenuation parameter Atp for a first situation is greater than a value of the attenuation parameter Atp for a second situation. The first situation represents a situation where each of the target MG torque Tm* and the target engine torque Te* is more than zero and the request torque Tall of the vehicle VEH1 is transiently increasing (see the period from time t11 to time t12 of FIG. 8). The second situation represents a situation where the request torque Tall of the vehicle VEH1 is in a steady state (see the period after the time t12 of FIG. 8). The situation where each of the target MG torque Tm* and the target engine torque Te* is more than zero shows that power output from each of the motor-generator 10 and the engine 22 is being transferred to the driving wheels 18.

The torque responsivity of the motor-generator 10 is higher than the torque responsivity of the engine 22. This brings the output torque Tm of the motor-generator 10 to have a dominant influence on the integrated output torque of the motor-generator 10 and the engine 22 while the request torque Tall of the vehicle VEH1 is transiently changing, i.e. is transiently increasing (accelerating). Thus, the second ECU 32C increases a value of the attenuation parameter Atp while the request torque Tall of the vehicle VEH1 is transiently changing as compared with a value of the attenuation parameter Atp while the request torque Tall of the vehicle VEH1 is in a steady state. This performs suppressing vibrations of the drivetrain of the vehicle VEH by the filter processor 32 d prior to improvement of the driver's drivability of the vehicle VEH1.

In contrast, the second ECU 32C decreases a value of the attenuation parameter Atp while the request torque Tall of the vehicle VEH1 is in a steady state as compared with a value of the attenuation parameter Atp while the request torque Tall of the vehicle VEH1 is transiently changing. This performs adjustment of the actual output torque Tm of the motor-generator 10 to follow the target MG torque Tm* with a higher responsivity prior to suppression of the vibrations of the vehicle VEH1. This therefore results in adjustment of the integrated torque of the motor-generator 10 and the engine 22 to immediately follow the request torque Tall of the vehicle VEH1, thus immediately satisfying the driver's acceleration request. This therefore improves the driver's drivability of the vehicle VEH1.

Each of the first to fourth embodiments can be modified as follows.

The limiter 32 b of the first embodiment performs the limiting task to gradually and continuously change the attenuation parameter Atp as the limited attenuation parameter Attr over time, but the present disclosure is not limited thereto. Specifically, the limiter 32 b of the present disclosure can perform a modified limiting task to gradually and stepwisely change the attenuation parameter Atp over time (see FIG. 9).

The limiter 32 b of the first embodiment gradually changes the attenuation parameter Atp in the form of a linear function as the limited attenuation parameter Attr, but can gradually change the attenuation parameter Atp in the form of an N-th order lag function as the limited attenuation parameter Attr; N is an integer equal to or more than 1. FIG. 10 schematically illustrates that the attenuation parameter Atp is changed in the form of a first order lag function as the limited attenuation parameter Attr.

The second embodiment can be modified to eliminate the limiter 32 b, and provide a limiter 32 g between the target attenuation-coefficient setter 32 c and the filter processor 32 d like the third embodiment.

The limiter 32 b can determine whether the rate, i.e. inclination, of change of the attenuation parameter Atp, in other words, the absolute amount of change of the attenuation parameter Atp per unit time, is equal to or higher than a predetermined first threshold rate, i.e. inclination.

Upon determination that the rate of change of the attenuation parameter Atp is equal to or higher than the predetermined first threshold rate of change, the limiter 32 b applies the limiting task to the attenuation parameter Atp to limit the rate of change of the attenuation parameter Atp.

Otherwise, upon determination that the rate of change of the attenuation parameter Atp is lower than the predetermined first threshold rate of change, the limiter 32 b does not apply the limiting task to the attenuation parameter Atp, thus outputting the attenuation parameter Atp as it is.

This configuration more efficiently balances between the improvement of suppressing vibrations of the drivetrain of the vehicle VEH and the improvement of the driver's drivability of the vehicle VEH.

Similarly, the limiter 32 g can determine whether the rate, i.e. inclination, of change of the target attenuation-coefficient ξ_(tag), in other words, the absolute amount of change of the target attenuation-coefficient ξ_(tag) per unit time, is equal to or higher than a predetermined second threshold rate, i.e. inclination.

Upon determination that the rate of change of the target attenuation-coefficient ξ_(tag) is equal to or higher than the predetermined second threshold rate of change, the limiter 32 g applies the limiting task to the target attenuation-coefficient ξ_(tag) to limit the rate of change of the target attenuation-coefficient ξ_(tag).

Otherwise, upon determination that the rate of change of the target attenuation-coefficient ξ_(tag) is lower than the predetermined second threshold rate of change, the limiter 32 g does not apply the limiting task to the target attenuation-coefficient ξ_(tag), thus outputting the target attenuation-coefficient ξ_(tag) as it is.

This configuration also more efficiently balances between the improvement of suppressing vibrations of the drivetrain of the vehicle VEH and the improvement of the driver's drivability of the vehicle VEH.

The degree of the Laplace operator s included in each of the denominator, i.e. the modeled transfer characteristics Gpm(s), and the numerator, i.e. the target transfer characteristics Gr(s), of the equation of the filter transfer characteristics I(s) according to each embodiment is set to 2, but can be set to 3 or more.

The target attenuation-coefficient setter 32 c of the first embodiment can set the target attenuation-coefficient ξ_(tag) when the limited attenuation parameter Attr becomes its maximum value to a value greater than 1. The target attenuation-coefficient setter 32 e of the second embodiment can set the target attenuation-coefficient ξ_(tag) when the limited attenuation parameter Attr becomes its minimum value to a value greater than 1.

The calculator 32 a of the second ECU 32C can adjust the attenuation parameter Atp such that a value of the attenuation parameter Atp for the first situation is smaller than a value of the attenuation parameter Atp for a third situation. The first situation represents a situation where each of the target MG torque Tm* and the target engine torque Te* is more than zero and the request torque Tall of the vehicle VEH1 is transiently increasing (see the period from time t11 to time t12 of FIG. 8). The third situation represents a situation where the request torque Tall of the vehicle VEH1 is transiently decreasing.

The target attenuation-coefficient setter 32 c of the first embodiment continuously increases the target attenuation-coefficient ξ_(tag) with an increase of the limited attenuation parameter Attr, but the present disclosure is not limited thereto. Specifically, the target attenuation-coefficient setter 32 c can increase the target attenuation-coefficient ξ_(tag) in several stages, such as three stages, with an increase of the limited attenuation parameter Attr. Similarly, the target attenuation-coefficient setter 32 e can decrease the target attenuation-coefficient ξ_(tag) in several stages, such as three stages, with an increase of the limited attenuation parameter Attr.

The filter processor 32 d can be installed in the first ECU 30.

The vehicle plant model for the modeled transfer characteristics Gpm(s) and the target transfer characteristics Gr(s) has output torque Tds of the drive shaft 16 as its output, but the present disclosure is not limited thereto. Specifically, a vehicle plant model having a rotational speed or a twisting angle θ of the drive shaft 16 as its output can be used as the vehicle plant model for the modeled transfer characteristics Gpm(s) and the target transfer characteristics Gr(s).

While illustrative embodiments of the present disclosure have been described herein, the present disclosure is not limited to the embodiments described herein, but includes any and all embodiments having modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alternations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. 

1. A control apparatus for a rotary electric machine of a vehicle, the vehicle being equipped with a drivetrain for transmitting power output from the rotary electric machine to driving wheels, the control apparatus comprising: a filter processor that filters target torque for the rotary electric machine to suppress a vibrational frequency component of the drivetrain using a filter having a frequency transfer characteristic; a controller that performs drive control of the rotary electric machine according to the filtered target torque; a parameter calculator that calculates, according to a running condition of the vehicle, a parameter associated with a request value for responsivity of output torque of the rotary electric machine with respect to the target torque; a variable setter that variably sets the frequency transfer characteristic of the filter to decrease a degree of attenuation of the vibrational frequency component with an increase of the request value for responsivity of the actual output torque; and a limiter that limits a rate of change of the degree of attenuation to suppress vibrations of the drivetrain.
 2. The control apparatus according to claim 1, wherein: the limiter comprises a gradual changer that performs a gradual change task to gradually change the degree of attenuation.
 3. The control apparatus according to claim 1, wherein: the drivetrain includes a drive shaft coupling between the rotary electric machine and the driving wheels; and the filter processor is configured to apply, to the target torque, a filtering process based on the filter having the frequency transfer characteristic, the frequency transfer characteristic being represented as a fractional expression of a target transfer characteristic over a modeled transfer characteristic, the modeled transfer characteristic comprising a frequency transfer characteristic of a plant model of the vehicle, the plant model having the output torque of the rotary electric machine as an input thereof, the plant model having, as an output thereof, an output parameter indicative of any one of output torque to the driving wheels, a rotational speed of the drive shaft, and a twisting angle of the drive shaft, the target transfer characteristic comprising a target frequency transfer characteristic of the plant model, each of the modeled transfer characteristic and the target transfer characteristic including an N-th order lag element where N is an integer equal to or more than
 2. 4. The control apparatus according to claim 3, wherein: the N-th order lag element included in the target transfer characteristic has a term including an attenuation coefficient; and the variable setter is configured to variably set the attenuation coefficient to increase the attenuation coefficient with an increase of the request value for responsivity of the actual output torque.
 5. The control apparatus according to claim 4, wherein: the variable setter is configured to: set the attenuation coefficient to a first value that causes the frequency transfer characteristic to be 1 when the request value of for the responsivity of the output torque becomes minimum; and set the attenuation coefficient to a second value equal to or more than 1 when the request value of for the responsivity of the output torque becomes maximum.
 6. The control apparatus according to claim 3, wherein: the N-th order lag element included in the modeled transfer characteristic has a term including an attenuation coefficient; and the variable setter is configured to variably set the attenuation coefficient to decrease the attenuation coefficient with an increase of the request value for responsivity of the actual output torque.
 7. The control apparatus according to claim 6, wherein: the variable setter is configured to: set the attenuation coefficient to a first value equal to or more than 1 when the request value of for the responsivity of the output torque becomes minimum; and set the attenuation coefficient to a second value that causes the frequency transfer characteristic to be 1 when the request value of for the responsivity of the output torque becomes maximum.
 8. The control apparatus according to claim 2, wherein: the gradual changer is configured to perform, as the gradual change task, a task to gradually change a rate of change of the parameter calculated by the parameter calculator.
 9. The control apparatus according to claim 4, wherein: the gradual changer is configured to perform, as the gradual change task, a task to gradually change a rate of change of the attenuation coefficient.
 10. The control apparatus according to claim 1, wherein: the drivetrain is capable of transferring the power output from the rotary electric machine and power output from an internal combustion engine installed in the vehicle to the driving wheels; and the variable setter is configured to variably set the frequency transfer characteristic of the filter such that the degree of attenuation of the vibrational frequency component for a first situation is greater than the degree of attenuation of the vibrational frequency component for a second situation, the first situation being a situation where the power output from the rotary electric machine and power output from the engine are being transferred to the driving wheels and the sum of the target torque for the rotary electric machine and second target torque for the internal combustion engine is increasing, the second situation being at least one of: a situation where the sum of the target torque for the rotary electric machine and second target torque for the internal combustion engine is in a steady state, and another situation where the sum of the target torque for the rotary electric machine and second target torque for the internal combustion engine is decreasing. 